I didn't mess with the internal pots. I know they are there... but I think there should be a certain level of inspired sound right out of the box. I just didn't feel it with that pedal. I own the Green Rhino (my favorite OD pedal, by far) and the Fat Sandwich... and they are both MONSTERS. The Pickle just didn't do it for me. There are dozens of other pedals out there I would buy before that one.
Also... I was using it for guitar... so maybe for bass it'll be different.
Update, I got one. Its fucking awesome on bass. Sounds pretty good on guitar too, when playing doom or soloing. You HAVE to mess with the internal trims like dickscraper said, made a world of difference. LOVE IT!